Apparatus for [ recording, ] transmission or reproduction of sound [ or images ] ; acoustic conduits [ ; recording devices for sound carriers; sound recording apparatus; electric cables; coaxial cables; commutators; compact discs featuring audio recordings of sounds to demonstrate the acoustic characteristics of loudspeakers; electric contacts; headphones; microphones; measuring instruments for use in acoustics, namely, acoustic meters; amusement apparatus and games adapted for use with television receivers or with video or computer monitors; electric sockets and electric contacts; amplifiers; electric couplings ]